In a portable device, a battery charger is commonly provided to charge a battery within the portable device. A battery charger that uses a switch-mode architecture can boost an output voltage at an output node, where a battery or other power supplying device is currently connected to, back to an input node when an input power supply is removed from the input node. This is referred to as reverse boosting. The battery charger may stay stuck in this undesirable state because it cannot distinguish that the input power supply has been removed. One typical approach to detect reverse boosting is to monitor an input voltage and an input current to the battery charger. However, for wireless charging, this approach may not work because of a lack of input current.